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Summary: Condensation of humid air is an important process in thermal and process engineering and a subject of many currently research-intensive scientific domains, such as atmospheric water harvesting and seawater desalination. The nature of (water) vapor condensation in the presence of non-condensable gas (NCG) such as air differs significantly from the case with the pure, quiescent vapor condensation. In the literature, simple models that describe the forced flow condensation of water vapor in the presence of air on a series of vertical flat plates are hard to find. Here we present a simple and computationally efficient semi-empirical correlation describing forced flow condensation from humid air inside vertical channels formed by flat plates. The correlation accounts air as a non-condensing gas, different heights of vertical plates, and different thermal-hydraulic parameters. The correlation has been experimentally validated and shows excellent agreement, as 90% of theoretically predicted values are within ±12% of experimental data.

The condensation of humid air is a crucial step in air conditioning and process engineering. However, the models that describe the condensation of vapour in the presence of a non-condensable gas require time-consuming numerical calculations that go beyond the Nusselt film theory. Only a small number of publications exist, where simple and computationally effective correlations for the condensation of water vapour in the presence of air are presented for specially designed condenser heat exchangers. Therefore, the objective of this paper is to extend the existing semi-empirical correlations for different geometries and process parameters. For the purpose of the study, an experimental setup with two different condenser heat exchangers based on vertical plates (height 74 mm) and horizontal tubes (3 tubes, diameter 40 mm and 7 tubes, diameter 15 mm) was built. Additionally, based on existing correlations, we developed two semi-empirical models that predict the condensation mass flux for the proposed geometries. Here, we report that the agreement between the experimental and theoretical values predicted by the new, semi-empirical correlations is excellent, with an average uncertainty of less than ±6%. Their usability was demonstrated by a possibly significant performance improvement of the condenser inside a condensation-type tumble dryer.

Worldwide, the novel coronavirus disease 2019 (COVID-19) has become a significant threat to global health. Worldwide, COVID-19 has affected the health service also in Slovenia. During this time, neurosurgery is facing difficulties in its service, both in emergency and elective surgeries. In the article, we describe the anti-COVID-19 measures taken at our neurosurgical department in a medical centre in Ljubljana, Slovenia, and analysed and compared the number of emergency and elective neurosurgical procedures during the time of the pandemic.

Background:One of the most common surgical operations for treatment of cervical spondylosis is anterior cervical discectomy with fusion (ACDF). In order to achieve stable fusion after discectomy and avoid dysphagia the artificial stand-alone zero-profile cages with integrated screws were developed and introduced into clinical practice. Outcome and complications after ACDF with such cages were not adequately assessed yet.Methods:We analyzed 20 consecutive patients with cervical spondylosis treated in our institution with ACDF with stand-alone zero-profile cage Zero-P. Before and after surgery and then 6, 12 and 24 months after surgery we assessed the level of pain with VAS scale, severity of myelopathy with mJOA scale and dysphagia with four level scale. Treatment outcome was assessed after 2 years according to Odom's criteria.Results:No complications occurred during surgery or recovery after surgery. The VAS score after surgery and then after 6, 12 and 24 months was statistically significantly lower than before surgery (pConclusions:Operative treatment of symptomatic cervical spondylosis with ACDF using stand-alone zero-profile cage with integrated screws is safe and efficient. Incidence of dysphagia after surgery is low and generally transient.

Background: Present paper describes our experiences with the use of three-dimensional (3D) reconstruction of medical images for pre-operative planning and intra-operative navigation in neurosurgery of cortical and sub-cortical tumors.Methods: In 10 patients with cortical and sub-cortical tumors, before surgery 3D models of tumor, normal nearby brain tissue and cortical veins were reconstructed from magnetic resonance images and in selected cases functional magnetic resonance images using the computer program »3D Slicer«. Based on these models, the skin incision, trepanation opening and trans-cortical approach to the tumor were planned in virtual 3D computer space. Collected positional data were transferred from the 3D computer space to the operation field using distances from the artificial and typical anatomical landmarks on skin and cortical surface.Results: Computer assisted 3D reconstruction provided a surgeon with more accurate localization of tumor than conventional mental reconstruction of the 2D medical images. In all cases the position, size and shape of skin incision, trepanation opening, cortical veins, sulci and gyri visualized on computer screen before surgery matched the actual anatomy observed during surgical procedure. In all patients the lesion was precisely found and macroscopically totally resected with minimal injury to the adjacent normal structures.Conclusions: Pre-operative computer assisted 3D reconstruction provides important additional information about spatial localization of cortical and sub-cortical tumors in comparison to mental reconstruction of 2D medical images. Therefore, it improves the accuracy of planning the surgical procedure and makes it less invasive and less risky.